Molecular compounds of o,o-dimethyl-carbamoylmethyl dithiophosphate and an alkyl phenol



y 1969 NOBORU MURAMOTO E L 3,444,273

MOLECULAR COMPOUNDS OF 0,0---DIMETHYLCARBAMOYLMETHYL DITHIOPHOSPHATE ANDAN ALKYL PHENOL Filed June 13. 1966 Sheet 0f 2 OH CF33 CH3 /00 90 60 4O20 0 CH United States Patent U.S. Cl. 260-943 4 Claims ABSTRACT OF THEDISCLOSURE Molecular compounds of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate and an alkyl phenol having the formula wherein R is abranched alkyl grOup having 3 or 4 carbon atoms and R is methyl ormethoxy group. These compounds are stable and are particularly useful asthe active ingredient in insecticidal compositions.

The present invention relates to an insecticidal composition comprisinga novel molecular compound of 0,0- dimethyl N-methylcarbamoylmethyldithiophosphate. More particularly, the invention relates to aninsecticidal composition comprising a novel molecular compound of0,0-dimethyl N-methylcarbamoylmethyl dithiophosphate of the formula,

CHaO S GHsO \SCH2CONHCH: with an alkyl phenol of the formula,

wherein R is a branched alkyl group having 3 or 4 carbon atoms and R isa member selected from the group consisting of methyl and methoxyradicals. Hitherto, 0,0- dimethyl N-methylcarbamoylmethyldithiophosphate, in spite of having an excellent insecticidal activity,has not been widely accepted because of the various unsolved questionsin connection with the formulation thereof. For example, the followingare named out as the drawbacks of the compound and the questions on itsformation still remain unsolved up to the time.

(1) Since the compound is relatively unstable, especially in thepresence of mineral carrier such as, for example, talc and clay, thecomposition formulated with such a carrier tends to be easilydecomposed, hence it is impossible to store the composition for a longduration of time.

(2) Since the compound per se and accordingly the composition thereofpossess an undesirable odor, it is diflicult to handle in practice.

(3) Since the compound possesses a higher water-solubility, theformulated composition, e.g. granular or dust formulation, applied tothe soil, is easily washed away in a shorter period of time, forinstance, by rainwater or subterranean water.

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Needless to say, the above mentioned drawbacks are all derived from thephysical and chemical properties of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate per se, therefore the key to the questions is how toimprove the properties of the compound itself.

Accordingly, an object of the present invention is to provide a novelmolecular compound of 0,0-dimethyl N-methylcarbarnoylmethyldithiophosphate having an improved stability and being tit for use inmaking a stable composition which can be stored for a long duration oftime under practical conditons.

Another object of the invention is to provide a novel molecular compoundof 0,0-dimethyl N-methylcarbamolymethyl dithiophosphate having adiminished undesirable odor and being fit for use in the control ofhousehold pests. Still another object of the invention is to provide anovel molecular compound of 0,0-dimethyl N- methylcarbamolymethyldithiophosphate having a reduced water solubility and an improvedresidual effect in the soil. A further object of the invention is toprovide a useful insecticidal composition containing the above-mentionednovel molecular compound of 0,0-dimethyl N- methylcarbamoylmethyldithiophosphate as an active ingredient. Still further object of theinvention is to provide a process for producing a novel molecularcompound of 0,0 iimethyl N-methylcarbarnoylmethyl dithiophosphatewithout loss of its insecticidal activity. Other objects of theinvention will be apparent from the description of this specificationand the claims hereinafter described.

In the present invention, it has been found that 0,0- dimethylN-methylcarbamoylmethyl dithiophosphate can be converted into a stablemolecular compound by contacting 0,0-dimethyl N-methylcarbarnoylmethyldithiophosphate with an alkyl phenol represented by the followinggeneral formula,

wherein R and R have the same meanings as defined above. Furthersurprising is the finding that all of the aforesaid objects can beattained by the provision of the said molecular compound of 0,0-dimethylN-methylcarbamoylmethyl dithiophosphate with the alkyl phenol compound.

Thus, taking a diiferent position from the conventional approaches toovercome the drawbacks of the compound the characteristic of the presentinvention is to utilize the unique properties of the novel molecularcompound obtained by contacting 0,0-dimethyl N-rnethylcarbamoylmethyldithiophosphate with said substituted phenol compound.

According to the infrared absorption spectrum of the present molecularcompound, it is apparent that oxygen atom in the carbamoyl moiety of thesaid phosphate is combined in an equimolar amount ratio with the hydroxyradical of the said alkyl phenol by means of a hydrogen bond.

The alkyl phenol compounds employed in the present invention arecharacterized in having at least one branched alkyl group containing 3to 4 carbon atoms, and one methyl or methoxy group. These conditions areempirically determined by the present inventors as the indispensableconditions for keeping the intermolecular bonding of the compound in anappropriate state and for giving an improved stability and a diminishedwater solubility. The molecular compound thus obtained by the meth- 0dof this invention has scarcely any undesirable odor and hygroscopicity.This compound also possesses an excellent thermal stability and can berecrystallized from such solvents as water, alcohol, xylene andperchloroethylene. These are indeed the characteristics of the presentmolecular compound, since the similar compound obtained by contacting0,0-dimethyl N-methylcarbamoylmethyl dithiophosphate with a phenolcompound having no branched alkyl group such as phenol, cresol andxylenol, does not possess such properties. In most cases, they arehygroscopic liquids having inferior thermal stabilit Iri considerationto increase of molecular weight, the novel molecular compounds of thepresent invention have the same insecticidal effectiveness as0,0-dimethyl N- methylcarbamoylmethyl dithiophosphate, besides withrelatively low toxicity to mammals compared with the said phosphate,especially the molecular compound consisting of the said phosphate and4-methyl-2-tert.-butylphenol with a half toxicity of the said phosphateto mammals, and have excellent sterilizing effect toward a wide varietyof pathogenic bacteria. Hence, they may be employed for one of the idealhousehold pesticides and useful disinfectants. Other properties such asan excellent systemic action into a plant, a diminished water solubilityand an improved stability, make the present molecular compound a veryuseful novel agricultural chemical.

In a preferred embodiment of the invention, 0,0-dimethylN-methylcarbamoylmethyl dithiophosphate is directly mixed with anequimolar amount of alkyl phenol defined above and the mixture is groundwell to effect the uniform admixing of the both components. If desired,the mixture may be heated to aid the uniform mixing thereof. In thiscase, an applying temperature needs not be too high to secure a completemelt of these components since the heating is a supplementary means toaid the reaction between them. Usually, a temperature of not more than60 C. may be advantageously employed. After cooling, the resultingsolidified mass may be pulverized and mixed together with an inertcarrier to make an appropriate formulation thereof. Alternatively, thefused mixture may be directl added with an inert carrier or sprayed intoice-water through a narrow opening to precipitate out the fine particlesof the product. In another preferred embodiment of the invention,0,0-dimethyl N- methylcarbamoylmethyl dithiophosphate and almostequivalent amount of alkyl phenol are heated in the presence of a smallamount of solvent, and the mixed solution is then cooled to precipitateout the crystals, followed by filtration, thereby to obtain the presentmolecular compound. In this case, the crystals isolated from the motherliquid are always of the equimolecular composition of these componentseven though somewhat differential amounts of reactants are employedtherein, hence to employ equivalent amount of the said phosphate and thesaid alkyl phenol is not always of indispensable condition in thisreaction. The melting point of thus produced molecular compound maywidely vary with the kind of employed alkyl phenol. For example, themelting point of the molecular compound obtained by contacting4-methyl-2-tert.- butyl phenol (M.P. 53 C.) with 0,0-dimethylN-methylcarbamoylmethyl dithiophosphate (M.P. 51 C.) is about 58 C.which is substantially higher than those of the employed raw materials.However, the melting points of the similar molecular compounds derivedfrom 4-methoxy- 2-tert.-butyl phenol and from 3-methyl-6-isopropylphenol are 43.5 C. and 33 C. respectively.

The equimolecular compound consisting of 4-methyl-2- tert.-butyl phenoland 0,0-dimethyl N-methylcarbamoylmethyl dithiophosphate isadvantageously employed for preparation of dust and wettable powder,because of having relatively high melting point. If desired, thiscompound obtained by contacting 6 mol of the said phosphate with 4 molof the said alkyl phenol may be also employed for formulation of aliquid preparation such 4 as oil preparation or paint, because of havingrelatively low melting point as is shown in FIG. 2.

The thus obtained molecular compounds of the present invention arecharacterized in having no undesirable odor as is found in 0,0-dimethylN-methylcarbamoylmethyl dithiophosphate. If desired, these compounds maybe further purified by the recrystallization method using a hydrocarbonsuch as xylene and toluene, chlorinated hydrocarbon such asperchloroethylene or the like.

The alkyl phenol compounds employed in the present invention may beeasily prepared from cresol or xylenol according to the conventionalmethod, whose details will not be required by those skilled in the art.As already described above, the present invention is characterized inemploying a novel molecular compound of 0,0-dimethylN-methylcarbamoylmethyl dithiophosphate as an active ingredient ofhousehold or agricultural pesticidal compositions. Furthermore, thepresent novel molecular compounds are characterized in having a goodstability and an excellent compatibility with other agriculturalchemicals and auxiliaries. Therefore, neither the particular conditionsnor the special instructions would be required for the formulation ofthe present insecticidal compositions. Thus the present novel molecularcompound can be easily formulated into dust, wettable powder, granule,emulsion or oil preparation according to various techniques which arewell known in the art. For example, the present molecular compounds maybe advantageously formulated with such solid carrier as clay, talc,kaolin and diatomaceous earth and such liquid carrier as xylene,kerosene, solvent naphtha, cyclohexanone, methyl ethyl ketone andperchloroethylene.

They can be also admixed with other insecticides, mitecides,nematocides, fungicides, herbicides and fertilizers at will. Thisinvention can be further illustrated by the following examples ofpreferred embodiments thereof although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention.

Example 1 Three point three grams of 4-methyl-2-tert.-butyl phenol (M.P.53 C.) was added to 4.6 g. of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate (M.P. 51 C.) in a mortar and the mixture was admixedhomogeneously to make a uniform mixture. The mixture gradually lost itsmoisture and changed its color into white. The thus obtained whitepowder possessed a new melting point of 58 C., which was substantiallydifferent from those of said raw materials. X-ray diffraction spectrumof the powder was shown in FIG. 1, which apparently indicated that thusobtained product is a new compound and not a mere mechanical mixture ofthese ingredients.

FIG. 2 showed a correlation between the compounding ratio of bothcomponents and the melting point of thus obtained product. From thisfigure, it is clearly understood that a novel molecular compound can beobtained at the time of using an equimolar amount of 0,0-dimethylN-methylcarbamoylmet-hyl dithiophosphate and alkyl phenol.

The above mentioned product was recrystallized from xylene for analysisuse. Thus, the product can be further purified by usingrecrystallization method with xylene or toluene to give highly pure,odorless crystals.

Example 2 Four point six grams of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate and 3.5 grams of 4-methoxy-2-tert.-butyl phenol wereadded with 6 cc. of xylene, and the mixture was heated at 45 C. to makea uniform solution. Upon cooling the solution to 5 C., 7.3 grams ofwhite crystalline mass were obtained. The melting point of this productwas 4344 C. and the result of an elementary analysis thereof coincidedwith the calculation based on an equimolar composition of bothcomponents.

Example 3 Four point six grams of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate and 3 grams of 3-methyl- 6-isopropy1 phenol weredissolved in 5 cc. of xylene at 40 C., and the mixture was cooled to -5C. to recover 6.0 grams of the crystalline mass (M.P. 33 C.). Theelementary analysis data were identical with the calculation based on anequimolar composition of both components.

Example 4 This example illustrates a reduced water solubility of thepresent molecular compound, which results in a high residualeffectiveness. Following Table 1 summarized the solubility data (percentby weight) of the compounds of Examples 1-3 in water and in xylene.

As clearly known from the above Table 1, the molecular compounds of thepresent invention show a remarkable decrease in the solubility in wateras compared with that of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate (i.e. almost one-tenth of the latter), but increase inthe solubility in a nonpolar solvent as xylene. This diminished watersolubility is a very desirable characteristic of the present molecularcompound since a long acting insecticidial composition may be providedtherewith.

The so-called systemic insecticide is usually applied to the soil andthe toxicant is absorbed through the roots into a plant, whereby thewhole plant body is toxicated for a desired period of time to preventfrom the attack of an injurious insect.

However, since 0,0- dimethyl N-methylcarbamoylmethyl dithiophosphatepossesses a higher water solu bility, it is easily Washed away from theapplied soil and hence it is ineffectual as a systemic insecticide. Onthe contrary, the diminished water solubility of the present molecularcompound breaks a new ground for the application of the compound in thisparticular field.

The following Table 2 summarized the easiness for extracting the activeingredient with water from 5% granular composition. In this test, each200 mg. of the granules (5% active ingredient and talc) were placed on afilter and washed with each cc. of distilled water. After combining thewashings, the extracted amounts of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate were analyzed.

The characteristics of relatively low washed-away ratio may beadvantageously utilized to abridge or alleviate any complex processes informulation.

Example 5 This example illustrates an excellent thermal stability of thepresent molecular compound. Thus, each 0.5 gram of 0,0-dimethylN-methylcarbamoylmethyl dithiopshosphate and each 0.5 gram of thepresent molecular compound were placed in a series of 2 cc. ampulesseparately. After sealing, these ampules were stored at 40 C., 60 C. and.1 10 C. for a predetermined period of time. The ampules were opened andthereafter the content of each ampule was developed by means of the thinlayer chromatography using a silica gel and 1:1 mixed solvent ofn-hexane and acetone and determined by using an infrared absorptionspectrum method. These results were shown in Table 3.

TABLE 3.THERMAL STABILITY, REMAINING PERCENT 40 0., 40 0., 40 0.,Compound Start 1 month 2 months 3 months 60 C., 60 0., 60 0., Start 5days 10 days 15 days 0., Start 1 hour *0,0-dimethylN-methylcarbamoylmethyl dithiophosphate. "Product of Example 1.

From this Table 3, it is apparent that the present novel compoundpossesses a superior thermal stability to the original 0,0-dimethylN-methylcarbarnoylmethyl dithiophosphate.

According to the studies of the inventors, it has been found that theaforesaid stabilization eifect is always found out in the atmosphere ofbeing capable of maintaining the original composition of said molecularcompound. For example, the present compound is very stable even in thepresence of such mineral carrier as talc and clay, as shown in Table 4.

This finding is very important since 0,0-dimethyl N-methylcarbamoylmethyl dithiophosphate is easily decomposed when it isformulated with such carriers. Thus, the present molecular compound canbe freely admixed with talc or clay to make a stable composition such asdust and granular formulation.

The following Table 4 illustrates as excellent compatibility of thepresent compound with such mineral carriers. In this test, each 5% dustformulation was kept at 40 C. for a designated period of time, andthereafter the decomposed active ingredient was determined by using thesame testing method as described hereinabove.

(Please refer to the test method of Table 3.)

TABLE 4 Decomposition rate (percent) 40 0., 40 0., Carrier Compound 1month 2 months Clay O,O-dimethyl N-methyl- 6. 9 18. 5

carbamoylmethyl dithiophosphate. Product of Example 1 0. 4 0.6 Talc0,0-dimethyl N-methyl- 13. 5 17. 0

carbamoylmethyl dithiophosphate. Do Product of Example 1 0.8 1. 2

Example 6 This example illustrates a superior bactericidal activity ofthe present molecular compound toward Staphylococcus aureus andEscherichia coli.

Using a phenol as the control, the bactericidal activity of the presentmolecular compound was shown in Table 5. In this table, all figures wereexpressed in terms of dilution ratio of the sample in which the testedmicroorganisms were not killed in minutes contact but killed in minutescontact.

TABLE 5 Sample St. aureus E. col

Phenol X80 X90 Product of Example 1 X2, 400 X1, 000 Product of Example2. X900 X800 Product of Example 3 X800 X000 As is apparent from theabove Table 5, the molecular compound of the present invention generallypossesses a strong bactericidal activity which is almost 10 timesstronger toward E. coli and 10-30 times stronger toward St. aureus thanthe respective activity of the phenol. Thus, the novel molecularcompound of the invention is useful not only as insecticides but also asdisinfectants.

Example 7 Forty eight grams of the product of Example 1 was mixed with42 grams of 300 mesh diatomaceous earth, 5 grams of white carbon and 5grams of the agricultural emulsifier Sorpol 5029, thereby to obtain awettable powder having a good water suspension ability.

Example 9 The emulsion concentrate of Example 7 was diluted with waterand thus obtained 5 times diluted emulsion was coated on a surface ofcm. x 15 cm. plywood at the rate of 50 ml./m.

A glass rink having a diameter of 10 cm. and being smeared with butteron the inside-wall thereof was placed on the board and 10 adultcockroaches (5 males and 5 females) were placed therein. After 60minutes contact with said coated board, the cockroaches were transferredin a new vessel, fed and the mortality was checked after 3 daysobservation period. In order to determine the residual effect of thepresent composition, said plywood board was kept in a room adjusted at atemperature of 27 C. and a relative humidity of 50 and the mortalitytests with elapse of time were repeated several times.

These results were shown in Table 6.

*Emulsifiable concentrate of 0,0-dimethyl N-methylcarbamoyl' methyldithiophosphate.

Emulsifiable concentrate of 0,0-dimethyl-O-(3-methyl-4-nitro phenyl)thiophosphate.

In each 500 ml. beaker, a culture bed comprising rice straw, fishpowder, and dry yeast, was prepared and housefly larvae wererespectively put on the beds kept in a thermostat at 27 C. and RH 60.

After 3 days later from the hatching of housefly eggs, each 1 ml. ofdiluted pesticidal compositions shown in Table 7 was respectivelysprayed on the surface of the said individual culture bed and themortality of larvae was observed 5 days later from said spraying. Stillliving pupae and larvae were placed in a culturing room and the emergedfly number were calculated.

These results were shown in Table 7.

TABLE 7 Mortality I Dilution (percent) Emerged fly Composition withwater of larvae (percent) Emulsion of Example 7 X200 08. 9 0. 2 X 1, 00007. 5 1. 3 X5 000 92. 9 6. 8

Wettable powder of X200 08. 6 0. 3 Example 8. X1, 000 98. 5 0. 4 X5, 0009G. 4 3. 4

0,0 dimethyl N -n1ethyl- X200 96. 2 O. 3 carbanloymethyl dithio- X 1,000 94. 4 2. 1 phosphate emulsion. X5, 000 90. 2 3. 5

0,0-dimethyl-O-(3-methyl-4- X200 97. 4 2. 2 nitro-phenyl) thiophos- X1,000 76. 8 20. 3 phate emulsion. X5, 000 8. 2 87. 5

Non treatment 1 0 90. 0

*Dilution is expressed by the times of active ingredient.

Example 10 TABLE 8 Composition The acute oral LD50 value (moi/kg.)

Emulsion of Example 1 1.20X10- Control 5.80X10- What we claim is:

1. A molecular compound composed of 0,0-dimethyl N-methylcarbamoylmethyldithiophosphate and an alkyl phenol of the general formula wherein R isa branched alkyl radical having 3 to 4 carbon atoms at the 2- or6-position and R is a methyl or methoxyl radical at the 3- or4-position.

2. A molecular compound defined in claim 1, wherein the said alkylphenol is 4-methyl-2-ter.butyl phenol.

3. A molecular compound defined in claim 1, wherein the said alkylphenol is 4-methoxy-2-ter.butyl phenol.

4. A molecular compound defined in claim 1, wherein the said alkylphenol is 3-methyl-6-isopropyl phenol.

References Cited UNITED STATES PATENTS 8/1965 Bouillenne-Walrand et a1.

CHARLES B. PARKER, Primary Examiner.

ANTON H. SUTTO, Assistant Examiner.

US. Cl. X.R.

